Lettie appears in some trees as "Lydia" Simpson, though the name Lydia is an error, derived from a record for another person, a Lydia Adams who appears in the 1840 Surry County census; this Lydia has no connection to Lettie, who had emigrated to Kentucky long before 1840. There are no original records that show her name as Lydia - she appears in every record simply as Lettie.
